Galactose-1-phosphate accumulation by a Duarte-transferase deficiency double heterozygote.

An infant, suspected of having galactosemia following a positive screening test on dried blood spots, was shown to be a Duarte-transferase deficiency compound heterozygote through studies of electrophoretic mobility of the transferase enzyme in blood from the patient and family members. No rise in blood glucose was seen following oral ingestion of galactose. At the same time, galactose rose in plasma and was excreted in the urine; galactose-1-phosphate accumulated in erythrocytes. A galactose-free diet was considered the prudent course in the presence of the patient's inability to metabolize galactose completely.